The embassy will take at least five working days to process your documents. Once the documents are processed, you will be issued a fully stamped Visa. Although this process offers you the benefit of obtaining a fully stamped Visa before leaving for Vietnam, it is expensive and time consuming. 

If you decide to apply for Visa to Vietnam by correspondence, then you will have to submit your documents to the embassy by postal mail. This is highly risky as you will have to send in all your documents, including your original passport, through postal mail. This means that you could lose your documents if your package is misplaced or lost in transit. 

An easier alternative to this method is Visa on Arrival. In order to apply for Visa on Arrival, you will have to get in touch with a travel agent based in Vietnam. You will have to fill up an online application form with your details such as your name, occupation, duration of stay and purpose of visit. While mentioning your purpose of visit, you will have to choose from options such as business, tourist and transit. Business Visa comes with a validity one month, three months and six months. A tourist Visa offers validity of one month and transit Visa offers a validity of less than five days. 

Usually online application forms are processed in two or three days. Once the form is processed, you will be issued a letter of approval. This letter of approval can be collected by your travel agent and forwarded to you. On reaching Vietnam, you will have to submit this letter at the Visa on Arrival counter of the airport you arrive in along with the Visa stamping fees for collecting your Visa on Arrival. 

It is to be noted that the Visa on Arrival process is extended only to those travelers who arrive in Vietnam by air.